This circuit is for a siren that can be used with any of the above alarms and also other types. The circuit is from a Radio Electronics magazine from May 1975.
This circuit, found in a 1988 documentation consisting of an audio switch that turns off the load...
This stabilized source can supply currents up to 200 mA with the indicated transistor or 500 mA...
With the shadow over the sensor, it is possible to interrupt the sound of your amplifier using this...